Sensor for in-floor conveyors

ABSTRACT

A sensor for use in an in-floor truck-towing conveyor switching mechanism, the sensor utilizing two cooperating jaws which together are engaged by a selector pin pulled between the jaws by the truck on which it is mounted. One of the jaws is fixed and the other is pivoted for movement toward and away from the fixed jaw under the influence of the pin. Pivotal movement of the movable jaw causes a cable connected to the switch plate or responder to be pulled, actuating the responder so as to switch the truck to a spur or branch track. The jaws of the sensor are biased to project above the floor. Both of the jaws are horizontally pivotable so as to depress under the floor when engaged by an object other than the selector pin, such as a vehicle wheel, thereby preventing accidental actuation of the responder.

United States Patent Bildsoe [54] SENSOR FOR IN-FLOOR CONVEYORS Jorgen S. Bildsoe, Royal Oak, Mich.

Raplstan Incorporated, Grand Rapids, Mich.

[221 Filed: Mar. 31, 1970 [21] Appl. No.: 24,080

[72] Inventor:

[73] Assignee:

[ 51 May 30, 1972 Primary Examiner-Arthur L. La Point Assistant Examiner-Robert Saifer Attorney-Price, Heneveld, Huizenga & Cooper [57] ABSTRACT A sensor for use in an in-floor truck-towing conveyor switching mechanism, the sensor utilizing two cooperating jaws which together are engaged by a selector pin pulled between the jaws by the truck on which it is mounted. One of r the jaws is fixed and the other is pivoted for movement toward and away from the fixed jaw under the influence of the pin. Pivotal movement of the movable jaw causes a cable connected to the switch plate or responder to be pulled, actuating the responder so as to switch the truck to a spur or branch track. The jaws of the sensor are biased to project above the floor. Both of the jaws are horizontally pivotable so as to depress under the floor when engaged by an object other than the selector pin, such as a vehicle wheel, thereby preventing accidental actuation of the responder.

6 Claims, 9 Drawing Figures Paiented May 30', 1972 3 Shcetsihce t. 1

I NVENTOIL Patented May 30, 1972 3 Sheets-Sheet Z INVENTOR. JORGE a, 8/10.;45

SENSOR FOR IN-FLOOR CONVEYORS BACKGROUND OF THE INVENTION In-floor conveyors of the track and chain type conventionally have main tracks and spur tracks, and switching means to divert the trucks engaged by the chains from one track to the other. For automatic operation, the switches are provided with sensors which selectively detect individual trucks so as to shunt or divert the proper truck at the proper switch. This is accomplished by the sensor activating a switch responder or switchplate when the sensor is triggered by the individual truck to be diverted at that switch.

One construction for such a system utilizes a sensor having a member which is depressed below the floor by a selector pin carried by the truck. This action by the selector pin on the sensor mechanically triggers the responder to block the main track and to divert the towing pin of the truck into the branch track. An example of such a system is disclosed in US. Pat. No. 3,316,856. The difficulty with such a system in which the sensor is activated by being depressed below the floor is that the sensor can be erroneously activated by any object which moves across the floor surface, such as the wheel of a truck.

Attempts have been made to avoid the above-described disadvantage present in sensors which rely on a vertical movement of the sensor to activate the responder. An example of the latter is disclosed in U. S. Pat. No. 3,261,300 wherein protector guards are mounted on both sides of a treadle, the latter being rotated between the protector plates only when a selector pin moves between those plates. The entire protector plates and treadle are mounted pivotally to be depressed into the floor without actuation of the treadle such as will occur when a vehicle wheel passes over it. Yet, the structure of the type disclosed in the aforesaid U.S. Pat. No. 3,261,300 has several remaining disadvantages. First of all, the depressible platform mounting both the protector plates and the treadle pivot about an axis which parallels the axis of rotation of the treadle when activated by the selector pin. Thus, a force acting in the direction most likely to depress the platform, namely in a direction transverse to the axis of rotation of the platform, is also capable of triggering the treadle inasmuch as the treadle pivots in a plane parallel to the direction of the aforesaid acting force. Also, there is no positive engagement of the selector pin by the treadle insuring that the latter will rotate sufficiently to activate the switch responder. Instead, the system relies on a simple abutting or pushing force which would be inoperative in the event that for some reason the selector pin was carelessly mounted causing it to ride over the treadle, or in the event the selector pin was not mounted at the correct height.

SUMMARY OF THE INVENTION This disclosure relates to a sensor utilized in a switch for an in-floor conveyor, the sensor serving to operate a switch plate or switch responder to divert a truck from one track to another.

Specifically, the invention provides a sensor which utilizes cooperating jaws that mutually engage the selector pin so as to detect by gripping its thickness independently of the pin's height from the floor, one of the jaws being stationary with respect to the path of movement of the selector pin. To

, prevent accidental actuation, both jaws are pivotally mounted about a horizontal axis so as to be depressible below the surface of the floor. The vertical movement is at a right angle to the pivot movement of the movable jaw in response to a selector pin.

Accordingly, it is an object of the invention to provide a sensor for an in-floor conveyor switching mechanism wherein the sensor reacts only to engagement between the sensor and the signaling portion of the truck.

It is a further object of the invention to provide a sensor of the above character wherein the sensor is mounted so as to be depressible below the floor by objects other than the signaling portion of the truck which engage it.

Another object of the invention is the provision of a sensor which positively differentiates between a truck mounted sensor and all other objects.

Other objects and advantages will become apparent upon reference to the following drawings and detailed discussion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a sensor constructed in accordance with the invention, the cover plate being removed for clarity;

FIG. 2 is a sectional view taken along the line lI-II of FIG. 1, the cover plate being in position;

FIG. 3 is a sectional view taken along the line III-III of FIG.

FIGS. 4 and 5 are fragmentary, partially schematic plan views of the switching mechanism utilizing the invention;

FIG. 6 is a fragmentary plan view, partially broken away, of the responder illustrated in FIGS. 4 and 5;

FIG. 7 is a fragmentary sectional view taken along the line VIIVII of FIG. 6;

FIG. 8 is an enlarged fragmentary plan view similar to FIG. 6, with the responder broken away to show additional details; and

FIG. 9 is a fragmentary perspective view of the end portion of a truck towed by the conveyor, the portion illustrating the selector pin positions.

DESCRIPTION OF THE PREFERRED EMBODIMENT As used throughout this application, directional words such as vertical" and horizontal are applied to the orientation of the parts described when they are in the in-floor installation.

The invention concerns an in-floor or sub-floor conveyor system wherein chains move through tracks below the surface of the floor 8 (FIGS. 4, 5 and 7), the chains being especially adapted to tow a truck 10 by engaging a downwardly depending pin 12 (FIG. 9). The tracks in which the chains move comprise at least one main track 14 and at least one branch track 16 extending from the main track (FIG. 6). Specifically, the

invention concerns the switching mechanism utilized to divert the pin and therefore the truck 10 from the main track 14 to the branch track 16. (See FIGS. 4 and 5.) The actual switching is accomplished by a switch tongue or responder 22 which is connected by a cable 24 to a sensing mechanism or sensor 40 designed to automatically actuate the responder 22 in accordance with a selector pin engaging the sensor as the truck to be switched passes over the sensor. The cable 24 passes under the tracks as shown in FIGS. 4 and 5. The selector pin 36 is mounted in any one of the several holes 32 either of two end plates 26 and 28 positioned on both sides of a frame 30 holding the pin 12 of the truck. Thus, it will be apparent that the sensor 40 is positioned a different distance from the track 14 at each switch location, the distance representing the distance one of the holes 32 is from the position of the pin 12 on the truck 10. More specifically, the distance from the track 14 to the line AB through the sensor 40 corresponds to the distance of one of the holes 32 to the pin 12. Thus, by selection of the particular hole 32 into which the pin is inserted, the particular switch which will be actuated is determined.

THE SENSOR Referring now to FIGS. 1 through 3, the sensor 40 is mounted in a housing 42 bolted or otherwise suitably secured below the floor 8, the housing being generally rectangular and having the long dimension extending parallel to the track 14. A bracket 44 having upstanding sides 46 is secured as by bolts to the bottom of the housing 42, and has mounted thereon a shaft 48. As shown in FIG. 2, the shaft 48 is mounted horizontally parallel to the floor 8.

The sensor 50 includes a normally horizontally extending sensor arm 52 pivotally mounted at one end on the shaft 48. Affixed to the other end of the sensor arm 52 is an upstanding jaw section 54. The jaw section 54 has a camming surface 56 on one side thereof and a somewhat spherical-like exterior surface 58. The surface 58 is smoothly rounded so as to present a smoothly blunted projection when biased upwardly through the opening 59 in the floor 8, as illustrated in solid lines in FIG. 2.

A rocker plate 60 is mounted on the arm 52 by a vertically extending pivot pin 62 for pivotal movement in a generally horizontal plane. The rocker plate, intermediate its ends, has a laterally extending finger 69. The pivot pin 62 engages this finger and, thus, is offset to the side of the main body of the rocker plate. The rocker plate 60 has a vertically extending jaw section 64, one vertical side of which has a camming surface 66. The other surface of jaw portion 64 has a surface 68 similar to the surface 58 of the jaw section 54 so as to present a blunted or rounded surface similar to surface 58. The camming surfaces 56 and 66 are opposed to each other (FIG. 1), the surfaces 56, 66, 58 and 68 thus giving the jaw portions 54 and 64 the appearance and shape of a cloven hoof.

The rocker plate 60 has an end portion 70 extending oppositely to the jaw section 64. The end of the portion 70 is engaged by a compression spring 72, the opposite end of which is seated in a boss 74 mounted on the rocker plate 50. The rocker plate 60 also has an ear 80 extending oppositely from the finger 69 and generally aligned with it (i.e. generally aligned along the plane C-D) (FIG. 1). An anchor pin 82 is mounted on the ear 80. The anchor pin 82 is offset from the main body of the rocker plate oppositely from the pivot pin 62. A screw 84 or other clamp means secures the cable 24 to the anchor pin. A plate 86 with a bushing 88 is secured to the floor of the housing 42 to guide the cable 24 as it reciprocates within the conduit 89.

The sensor arm 50 and the jaw sections 54 and 64 mounted thereon are biased upwardly so as to project the jaw portions above the floor level, by means of a compression spring 100 mounted vertically in a socket 102 mounted on the frame 44 (FIGS. 2 and 3).

From FIGS. 1 and it will be noted that the jaw section 54 has its inside surface generally parallel to the centerline of the chain track 14 and the jaw section 64 is inclined at an angle to it. The curved or rounded ends 56 and 66 of the jaws face upstream of the conveyor (that is, the direction from which the sensor pin 36 approaches the sensor) and are spread apart. The downstream or opposite ends of the jaws engage or almost engage each other, forming a V-shaped sensor 90 opening or channel between them. At its upstream end the channel is as wide or wider than the width of the sensor pin 36 but at its downstream end is substantially smaller.

The operation of the sensor is as follows: Because jaw portion 64 is biased by spring 72 toward jaw portion 54, the camming surfaces 56 and 66 center the selector pin along line AB as the pin approaches the point where it is mutually engaged by both jaws. At this point, because the jaw portion 54 and its camming surface 56 are immovable in any horizontal plane, they provide a fixed stop engaging one side of the pin. As the pin continues to travel through the channel 90, it forces the movable jaw section 64 to separate from the fixed jaw section 54. As the jaw section 64 shifts, it pivots the rocker plate 60 about the pivot pin 62. Since the jaws are affected only by the diameter or thickness of the sensor pin, the sensor is actuated, so long as the spacing of the pin from the floor does not exceed the height of the jaw sections 54 and 64. The pivotal movement of the rocker plate 60 causes the pin 82 to pull the cable 24 in a direction parallel to the track 14 which in turn pivots the responder 22 in a manner hereinafter described. In the event the jaw portions 54 and 64 are contacted by an ob ject other than the selector pin, such as by a wheel, the jaw members are depressed below the surface of the floor to the dotted position shown in FIG. 2, by pivoting about the shaft 48. This movement does not shift the cable 24 since it does not cause pivotal movement of the rocker plate 60 about the pivot pin 62. The rounded surfaces 58 and 68 insure that the contact with the jaws by such other objects is not an abrupt one but rather a smooth contact. This eliminates injury to both the passing object and to the sensor itself. Once the object has passed over the jaw members, the spring rotates the jaws to their normal erected position.

THE RESPONDER Referring now to FIGS. 4 through 8, the responder includes switch tongue 22 having double plates and 132 welded together and to a bushing 134. The bushing 134 rotates on a stub axle 136 secured to the base 170. The plate 130 is designed to divert the truck pin and therefore the truck from the track 14 to the spur track 16 when in the position shown in FIG. 5, and to preclude the truck pin from moving into the spur track 16 when in the position shown in FIGS. 4 and 6. To that end, the plate 130 is provided with a pointed end 140 and a camming side 141 for contacting and diverting a truck pin. To seat the end 140 when the tongue 22 is closing the spur track the track 14 has an undercut or recess 142 (FIG. 7) in one side. To seat the point 140 when the tongue 22 is in diverting position the opposite side of the track 14 has an undercut or recess 146 (FIG. 6). The cavities are closed at the top by the outer edge 154 of the track, to prevent the truck pin 12 from lodging therein. Because the end 140 of the plate 130 slides under the track in either the diverting or the retracted position, the end 150 of the upper plate 132 is cut back so as to clear the track. This end 150 is shaped to abut against the outer edge 154 of the track 14, thereby limiting the movement of the responder 22 when it is switched into the diverting position and bracing it against the shock generated by the truck pin slamming into it. When the tongue 22 is retracted (FIG. 6) the side 156 of the plate 130 forms a continuation of the adjacent side of the main track 14.

A locking arm 160 (FIGS. 6 and 8) depends from the lower plate 130 and radially from the bushing 134, the plate 160 being welded or otherwise attached to both the bushing and to the lower plate. A flange 162 projects from the locking plate 160 and has mounted thereto one end of a tension spring 164. The opposite end of the tension spring isconnected as by a bolt 168 to the base 170. The spring 164 and the plate 160 thus bias the bushing 134 and the tongue 22 to rotate clockwise as shown in FIG. 6 so as to position the plates 130 and 132 in the diverting position. The tongue 22 is prevented from moving to the diverting position by a trip lever journalled to a shaft 182 mounted below the floor surface 8. A tension spring 184 is hooked to the end 186 of the lever 180, the opposite end of the spring 184 being hooked to a bracket 186 mounted below the floor (FIG. 7). A hook 190 secures the end of the cable 24 to the lever 180 between the shaft 182 and the end of the lever engaging the plate 160 (FIG. 6). When the cable 24 is pulled by the actuation of the sensor 40, the lever 180 rotates clockwise, as shown in FIGS. 6 and 8, against the action of the spring 184. The end of the lever 180 opposite the spring 184 has a curved notch 192 especially adapted to en.-' gage the locking plate 160.

Thus, it will be apparent that upon movement of the cable 24 due to the activation of the sensor, the lever 180 is pulled away from the locking plate 160. The locking plate and the tongue 22 rotate under the influence of the spring 164, thereby moving the tongue into diverting position, as shown in FIG. 5. The cable 24 releases as soon as the sensor 40 is disengaged from the selector pin. However, the tongue 22 will remain in diverting position until it is forcibly shifted back to its original position shown in FIGS. 6 and 8 by the engagement of the heel 200 by the truck pin 12. When this happens the spring 184 will automatically shift the lever 180 to locking position.

It will be recognized that the connection between the sensor and switch need not necessarily be a cable. The connection could be electrical with the pivotal movement of the rocker plate 60 closing a switch which in turn actuates a solenoid to cause the switch to shift positions. Alternately the connection could be pneumatic or hydraulic with a valve substituted for the switch and piston and cylinder assembly substituted for the solenoid. In both cases it will be recognized that depressing the jaw assembly flush with the floor will generate no signal since this will not cause separation of the jaws. It will also be recognized if an object enters the passage between the jaws but they are simultaneously depressed for some reason, no switch reaction will result because the downward movement of the jaws will cause the actuator pin to withdraw from the passage. Thus, whether the connection between the sensor and the switch is mechanical, electrical or by other means the signal generating mechanism of the sensor will be rendered inoperative by depression of the sensor. This is very important in preventing the generation of false signals such as by the passage of vehicles not connected with the conveyor.

RESET MECHANISM FOR THE RESPONDER The end of the plate 130 opposite the point 140 is provided with a heel portion 200 shaped to project out into the spur track 16 when the tongue 22 is rotated to the diverting position shown in FIG. 5. It will be immediately apparent that when the truck pin starts its travel along the track 16, it cams against the heel portion 200. This pivots the tongue 22 back to its retracted position shown in FIG. 4. In retracting the responder acts against the bias of the spring 164 until the locking plate 160 seats in the notch 192 of the lever 180. The lever 180 is provided with a cooperating curved edge 202 which accommodates the end of the locking plate as it rotates back into the locked position.

ALTERNATE EMBODIMENTS Other equivalent embodiments will be apparent to those skilled in the art, in addition to the preferred embodiment disclosed herein. For example, instead of the responder being mechanically actuated by the cable, the sensor could trigger an electric signal which actuates a solenoid, the latter in turn releasing the responder. Or the plates 130 and 132 can be combined into one single plate shaped in the manner disclosed for plates I30 and 132, thus allowing the pointed end 140 to slip under the track so as to not interfere with the truck pin as it moves down the track. Also, the lever 180 or an additional lever can be utilized for other purposes, such as to block the actuation of the responder in the event the spur track is full, even though the sensor has been triggered by a selector pin.

Thus, it is intended that the invention cover these alternate embodiments as well, unless the following claims by their express language state otherwise.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

1. A sensor for a switching mechanism for an in-floor conveyor for controlling the movement of a vehicle connected to said conveyor and having a sensor actuator, the sensor having an actuator contacting element projecting above the floor, the improvement in said sensor comprising:

said element having a pair of upstanding actuator contacting sections movable with respect to each other;

plate means supporting said sections for vertical movement between an extended position projecting above the surface of the floor and a retracted position wherein their tops are depressed generally flush with said floor surface; mounting means for said plate means holding said plate means against movement normal to said vertical movement, one of said sections being fixed to said plate means,

the other of said sections being pivotally mounted on said plate means for movement in a horizontal plane toward and away from said fixed section;

means biasing said plate means and said sections into said extended position;

means biasing said movable section toward said fixed section to form a passage for said actuator a portion of which is narrower than said actuator whereby movement of said actuator through said passage forces said sections apart;

a switch responsive to movement of said movable section;

and means connecting said movable section to said switch;

said switch being fixed against vertical movement;

said connecting means allowing vertical movement of said plate means with respect to said switch without actuating said switch.

2. A sensor as described in claim 1, wherein said passage is V-shaped with the end thereof upstream of the direction of movement of said conveyor being wider than the thickness of said actuator to facilitate the entry of the actuator into said passage.

3. A sensor as described in claim 1 wherein said movable section has an integrally extending arm member pivotable with said movable member about an axis generally perpendicular to the floor and wherein said connecting means is connected to said switch and said arm member.

4. A sensor as described in claim 1 and further including camming portions on said sections forming an entrance to said passage, said camming portions adapted to center and gradually engage said actuator.

5. A sensor as described in claim 4 wherein said sections include an outer surface shaped to present a blunted, gradually curved projection rising from the surface of the floor.

6. A sensor for a switching mechanism for an in-floor conveyor for controlling the movement of a vehicle connected to said conveyor and having a sensor actuator, the sensor having an actuator contacting element projecting above the floor, the improvement in said sensor comprising:

said element having a pair of upstanding actuator contacting sections movable with respect to each other; plate means supporting said sections for vertical movement between an extended position projecting above the surface of the floor and a retracted position wherein their tops are depressed generally flush with said floor surface;

mounting means for said plate means holding said plate means against movement normal to said vertical movement, one of said sections being fixed to said plate means, the other of said sections being pivotally mounted on said plate means for movement in a horizontal plane toward and away from said fixed section;

means biasing said plate means and said sections into said extended position;

means biasing said movable section toward said fixed section to form a passage for said actuator a portion of which is narrower than said actuator whereby movement of said actuator through said passage forces said sections apart;

a switch responsive to movement of said movable section;

and

means connecting said movable section to said switch;

each of said movable and fixed sections having ends with generally facing rounded portions forming an entrance to said passage, said generally facing rounded portions adapted to center and gradually engage said actuator. 

1. A sensor for a switching mechanism for an in-floor conveyor for controlling the movement of a vehicle connected to said conveyor and having a sensor actuator, the sensor having an actuator contacting element projecting above the floor, the improvement in said sensor comprising: said element having a pair of upstanding actuator contacting sections movable with respect to each other; plate means supporting said sections for vertical movement between an extended position projecting above the surface of the floor and a retracted position wherein their tops are depressed generally flush with said floor surface; mounting means for said plate means holding said plate means against movement normal to said vertical movement, one of said sections being fixed to said plate means, the other of said sections being pivotally mounted on said plate means for movement in a horizontal plane toward and away from said fixed section; means biasing said plate means and said sections into said extended position; means biasing said movable section toward said fixed section to form a passage for said actuator a portion of which is narrower than said actuator whereby movement of said actuator through said passage forces said sections apart; a switch responsive to movement of said movable section; and means connecting said movable section to said switch; said switch being fixed against vertical movement; said connecting means allowing vertical movement of said plate means with respect to said switch without actuating said switch.
 2. A sensor as described in claim 1, wherein said passage is V-shaped with the end thereof upstream of the direction of movement of said conveyor being wider than the thickness of said actuator to facilitate the entry of the actuator into said passage.
 3. A sensor as described in claim 1 wherein said movable section has an integrally extending arm member pivotable with said movable member about an axis generally perpendicular to the floor and wherein said connecting means is connected to said switch and said arm member.
 4. A sensor as described in claim 1 and further including camming portions on said sections forming an entrance to said passage, said camming portions adapted to center and gradually engage said actuator.
 5. A sensor as described in claim 4 wherein said sections include an outer surface shaped to present a blunted, gradually curved projection rising from the surface of the floor.
 6. A sensor for a switching mechanism for an in-floor conveyor for controlling the movement of a vehicle connected to said conveyor and having a sensor actuator, the sensor having an actuator contacting element projecting above the floor, the improvement in said sensor comprising: said element having a pair of upstanding actuator contacting sections movable with respect to each other; plate means supporting said sections for vertical movement between an extended position projecting above the surface of the floor and a retracted position wherein their tops are depressed generally flush with said floor surface; mounting means for said plate means holding said plate means against movement normal to said vertical movement, one of said sections being fixed to said plate means, the other of said sections being pivotally mounted on said plate means for movement in a horizontal plane toward and away from said fixed section; means biasing said plate means and said sections into said extended position; means biasing said movabLe section toward said fixed section to form a passage for said actuator a portion of which is narrower than said actuator whereby movement of said actuator through said passage forces said sections apart; a switch responsive to movement of said movable section; and means connecting said movable section to said switch; each of said movable and fixed sections having ends with generally facing rounded portions forming an entrance to said passage, said generally facing rounded portions adapted to center and gradually engage said actuator. 